Single and Double Photonuclear Excitations in Pb+Pb Collisions at sqrt(s_NN) = 2.76 TeV at the CERN Large Hadron Collider

Abstract

Cross sections are calculated for single and double photon exchange in ultraperipheral Pb+Pb collisions at the LHC. The particle production is simulated with the DPMJET event generator. Large cross sections are found for particle production around mid-rapidity making these processes an important background to hadronic nuclear interactions at both the trigger and analysis levels.

Figures (4)

• Figure 1: Probability for having a photonuclear interaction and no hadronic interaction as a function of impact parameter for three different minimum photon energies, $k_{min}$.
• Figure 2: Pseudorapidity distributions of charged particles for different minimum photon energies for single (left) and double (right) excitations with different cut-off energies, $k_{min}$. For single excitations, the solid histograms are for photoproduction off the nucleus with negative rapidity and the dashed histogram corresponds to production off the nucleus with positive rapidity. The peaks around $\eta = \pm$ 9 are from knock-out protons from the target nucleus.
• Figure 3: Multiplicity distributions of charged particles at mid-rapity $| \eta | <$ 1 for single (left) and double (right) excitations with different cut-off energies, $k_{min}$.
• Figure 4: (a) Transverse momentum distribution of charged particles within $| \eta | <$ 1. (b) Fraction of events with at least one charged particle within $| \eta | <$ 1 as function of photon energy. (c) Same as (b) but for $| \eta | <$ 4.5.